Description:Recently, an interest in the study of oral candidiasis has markedly increased mainly because of its association with viral infections due to human immunodeficiency, but also because of its relation with potentially malignant lesions of oral mucosa. These lesions belong to the wide group of leukoplakia. Leukoplakia is a clinical term used to describe a range of nonspecific white lesions, whose appearance does not generally correlate well with histopathologic changes; therefore, biopsy should be performed in all cases to determine which are precancerous or potentially malignant ones. In order to study the association of Candida albicans and the types of mucosal lesions, we took 30 consecutive biopsies of oral mucosa and the smears for microbiologic examination from the changed surface of mucosa and from the rest of oral cavity. The study group consisted of 30 patients, 21 women and 9 men, with the average age of 50.23 years (range, 25-77 years). In 6 cases Candida was diagnosed in mucosal biopsy. In the smear from the lesion, it was present in 3 cases, and 2 cases were found in the smear from an unchanged oral mucosa. In 9/30 cases (30%) Candida was positive regardless of the smear area or mode of diagnosis. The most common lesion is leukoplakia, diagnosed in 12/30 cases (40%), in 6 female and 6 male patients. The average age of those patients was 52.42 years. The lesions were located as follows: cheek mucosa - 5 cases; gingival mucosa - 2; lower lip - 2; floor of the mouth - 2; soft palate - 1; Candida was present in 3/12 cases. The lesion with the second highest incidence is lichen planus (9 cases), with positive Candida infection in 4/9 (44.44%). Epithelial dysplasia, although diagnosed in a very small number of cases (1/30 or 3.3%) with leukoplakia, was associated with a Candida infection. Generally, Candida is present in potentially malignant oral mucosal lesions (in 3/12 or 25% of leukoplakia cases, in 4/9 or 44.44% of lichen planus cases, and 1/1 squamous papilloma), with an increasing incidence in lesions with serious dysplastic epithelial changes.